title: Heat sensitization of bacterial spores after exposure to ethidium bromide, acriflavine, or daunomycin.
abstract: A 20-min exposure of 10(7) unmodified spores of either Bacillus subtilis NCTC 3610 (harvested from potato-dextrose agar plus manganese) or Bacillus megaterium ATCC 19213 (harvested from nutrient agar plus manganese) per ml to 5 microgram of ethidium bromide per ml did not kill the spores (recovered on TAM [thermoacidurans agar modified]-plus thymidine medium). However, in both cases, the ability to survive various heat treatments was reduced after exposure of the spores to ethidium bromide. With B. subtilis, a 10-min heat treatment at 85 degrees C of unexposed spores resulted in an 85% survival rate, whereas only 50% of the ethidium bromide-exposed spores survived. With B. megaterium similar results were obtained at 75 degrees C; 77% of the unexposed spores survived, whereas only 31% of the ethidium bromide-exposed spores survived. Similarly, a 10-min exposure of B. subtilis spores to 0.005 microgram of acriflavine per ml did not kill unheated spores; however, the ability of the spores to survive exposure at 85 degrees C for 10 min was reduced to 40%. After exposure to 10 microgram of daunomycin per ml, the survival rate was 35%. Binding studies with ethidium bromide showed strong binding to spores, but as yet, the site of binding is unknown.
mesh_terms: D000166:Acridines / Q000494:pharmacology*; D000167:Acriflavine / Q000378:metabolism / Q000494:pharmacology*; D001410:Bacillus megaterium; D001412:Bacillus subtilis; D003630:Daunorubicin / Q000378:metabolism / Q000494:pharmacology*; D004996:Ethidium / Q000378:metabolism / Q000494:pharmacology*; D006358:Hot Temperature; D013171:Spores, Bacterial / Q000187:drug effects* / Q000502:physiology
chemical_list: D000166:Acridines; D000167:Acriflavine; D004996:Ethidium; D003630:Daunorubicin